Definitely a 10 bolt, I'm pretty sure it's an 8 1/2 " ring gear, and posi was an option.Numbers are stamped onto the right hand side of the axle tube about 3" out from the differential. Haynes manual doesn't have the codes for those numbers but Chiltons should. It tells the year of manufacture and the gear ratio. By '74 highway gears were in vogue, so figure on somewhere around 2.70:1. That's a guess, but it should be close.hope that helps.